The only horror games I played so far are the Dementium series and the Resident Evil: Deadly Silence. Just wondering if there are anymore horror games for the DS out there that I have not yet heard about?? Thanks in advance!

if language isn't a problem for you, you could try nanashi no game.
it's a horror game based on the same concept as the ring(movie), except with an old buggy RPG game replacing the cursed movie.(so instead of a movie about a movie that kills, it's a game about a game that kills)